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Timelapse: All spills of crude oil crude bitumen and synthetic crude in Alberta each year from 1975-2012. Each dot is one spill; dot size does not indicate spill size. Source: Energy Resources Conservation Board

Alberta’s had an average of two crude oil spills a day, every day for the past 37 years.

That makes 28,666 crude oil spills in total, plus another 31,453 spills of just about any other substance you can think of putting in a pipeline – from salt water to liquid petroleum.

It sounds like a lot. And it isn’t a number the provincial government throws around often.

Authorities point to a much more encouraging statistic: There were 1.5 incidents per 1000 kilometres of pipeline in 2011, and that figure’s been dropping for the past three years.

It’s true: According to a database of spills recorded by the Energy Resources Conservation Board and obtained by Global News, the number of spills, leaks and other unintentional releases of material by the oil and gas industry has been declining over the past decade or so.

The database provides a granular portrait of mishaps involving the oil in oil country.

But maybe more telling is what it doesn’t include: The regulatory body’s database is messy and missing data in many places; it doesn’t include any spills from some of the biggest pipelines – those crossing provincial or national borders. These fall under National Energy Board jurisdiction. For the 53 per cent of spills from somewhere other than a pipeline, such as oil wells and pumping stations, anything under 2 cubic metres (2,000 litres, or about twelve and a half barrels) doesn’t get counted.

And as Alberta makes the case for dramatically expanding its hydrocarbon veins within the province and to the other end of the continent, some are questioning just how close an eye authorities keep on the 2.5-million barrels of oil flowing through 400,000 kilometres of pipeline every day.